1. Field of the Invention
This invention relates to an analytical method and apparatus for analyzing substances, and more particularly to an analytical method and apparatus for analyzing substances such as a liquid substance like lubricating oil, the qualities of which may change as the time proceeds, whereby the modification or service life of the substance can be estimated or foreseen simply and precisely.
2. Description of the Related Art
Conventionally, for estimating or foreseeing the modification and service life of chemical substances the qualities of which may change as the time proceeds, like lubricating oils during use, fats and oils during storage, and so on, various chemical and physical analytical methods have been employed to measure the neutralization values and the viscosities of the substances.
Although the conventional methods are useful to know whether chemical substances have been modified, degraded or not, they have no effect for estimating or foreseeing the service life of the chemical substances.
In like manner, though infrared spectrography, gas chromatography, and the like are useful to elucidate the chemical structures of chemical substances, they are inefficient in estimating and foreseeing the modification and the service life of chemical substances. Moreover, it is impossible to analyze both of the light and heavy fractions of a chemical substance using only these analytical methods.
In brief, by any of the conventional analytical methods, it is very difficult to estimate and foresee the modification and the service life of a chemical substances in which the qualities may change with the passage of time, though it is generally recognized to be of great importance.
In view of the foregoing, the inventor has intensively studied to develop an analytical method and apparatus for analyzing a substance which, by surpassing the above-mentioned disadvantages of conventional analytical methods, realize the foreseeing or quickly recognizing the modification and service life of a liquid chemical substance such as a lubricating oil, etc.; in which the qualities may change with the passage of time. As a result of the extensive study, it has been found that the foreseeing or quickly recognizing as described above is facilitated by separating the liquid chemical substance at the proper temperature and pressure into light and heavy fractions, namely vapor and liquid fractions, and analyzing both of the fractions simultaneously.